The present invention relates to a wide picture plane/standard picture plane television signal receiving apparatus which can selectively receive a standard television signal having a standard picture plane in accordance with the NTSC system and a television signal, for example such as an EDTV (Enhanced Definition Television) signal, a MUSE (Multiple Sub-Nyquist Sampling Encoding) signal, or the like, originally having an aspect ratio of a wide picture plane, and which can perform picture display with a wide aspect ratio upon reception of either television signal.
Recent propagation of large-sized television receivers necessarily requires provision of a high precision picture. In such a movement, there has been proposed, as disclosed in Japanese Patent Unexamined Publication No. Sho-61-123295, an IDTV (Improved Definition Television) in which a frame memory is used to perform three-dimensional processing in a television signal receiving apparatus. In the IDTV, not only the vertical resolution is greatly improved when a still picture is sent in, but disturbance components peculiar to the standard television can be completely eliminated.
Further, researches on an EDTV (Enhanced Definition Television) in which high definition processing is performed at both the transmission and reception sides have been eagerly effected. Specific examples of such an EDTV can be seen, for example, in Japanese Patent Unexamined Publication Nos. Sho-63-78685 and Sho-63-36693.
In the EDTV, in addition to the attainment of high definition by the IDTV, it is intended to attain the improvement of horizontal resolution and the widening of the picture plane aspect ratio. The first generation EDTV system mainly includes techniques of insertion of a ghost elimination reference signal at the transmission side, performing three-dimensional signal processing by use of a frame memory at the reception side, and performing double speed scanning.
In the second generation EDTV, in addition to the above-mentioned techniques, it is expected that widening of a picture plane and insertion of high precision information become its main techniques. Although the method of the improvement of horizontal resolution and the widening of the picture plane aspect ratio is still in the stage of research, it is known that in an EDTV receiver, a non-interlacing picture having 575 scanning lines and a frame frequency of 60 Hz is displayed in a wide aspect display.
Moreover, the MUSE (Multiple Sub-Nyquist Sampling Encoding) system, which is a high definition television transmission system developed by Japan Broadcasting Corporation (hereinafter referred to as "NHK"), attracts public attention. The MUSE system is a so-called "Hi-Vision" system in which a high definition television video signal is transmitted in the condition of band compression. As for this transmission system, experimental broadcasting has been conducted, and periodic test broadcasting has been started since the spring of 1989 in Japan.
As described in the "NHK Technical Journal", Vol. 39, No. 2, Consecutive No. 172, 1987, pp. 1-53, the MUSE system is a system in which a luminance signal and a color difference signal are multiplexed on each other on a time base and picture elements are thinned so that the picture elements circulate by a pair of frames to thereby attain the band compression. In the MUSE system, it is defined that the signal is an interlacing signal having 1125 scanning lines and a frame frequency of 30 Hz and the aspect ratio of the picture plane is 16:9. Thus, the MUSE system is largely different in standard from the NTSC system which is the current broadcasting system.
In order to receive the signal in the foregoing system, it is necessary to use a receiver having a large-scaled circuit using a frame memory. Currently, the development of individual receivers separately for the EDTV system and the Hi-Vision system has been authorized. It is however supposed that a receiver capable of selectively receiving a plurality of broadcasting signals of those different systems by one and the same receiver will be required in the future.
At the present, however, there is no receiver in which existence of such a plurality of broadcasting systems different from each other is taken into consideration. It is the present situation that only a signal conversion device has been developed for enabling a current receiver to receive the Hi-Vision broadcasting. The signal conversion device is a so-called down converter which has been developed by NHK.
In the NTSC system which is the current broadcasting system, the signal is an interlacing signal having 525 scanning lines and a frame frequency of 30 Hz and the aspect ratio of the picture plane is 4:3. That is, a down converter is required to convert the number of scanning lines from 1125 to 525 and the aspect ratio of the picture plane from 16:9 to 4:3. In the down converters, there are two display modes which are shown in FIGS. 2A and 2B.
FIGS. 2A and 2B show the display areas of the down converters in each of which the thick-line frame shows a display of an aspect ratio of 4:3. In a first system, the aspect ratio is converted from 16:9 to 4:3 by cutting off the opposite right and left ends of a wide picture plane as shown in FIG. 2A. In a second system, the opposite upper and lower ends of a picture plane of the current display system are cut off so that a picture of 16:9 can be displayed on the display of 4:3. These two systems are effective means for displaying a picture of a wide aspect ratio in the current display of 4:3.
The down converters of those two display modes have the following problems. That is, the down converter of the first mode in which the opposite right and left ends of the picture plane of the Hi-Vision signal are cut off has a problem (1) that the information is omitted at the right and left sides of the picture plane and another problem (2) that the vertical resolution is lowered. On the other hand, the down converter of the second mode in which the opposite upper and lower ends of the current picture plane are cut off has a problem (3) that the vertical resolution is further lowered, and another problem (4) that the blanking period appears in the picture plane of the display.
The above problem (1) is caused by making the aspect ratio of the MUSE signal coincident with the aspect ratio of the NTSC signal, so that the opposite right and left side portions which are visible in the Hi-Vision system becomes invisible in the case of using the down converter. In the case of a video signal of, for example, characters or the like, it becomes impossible to read the characters or the like, and therefore this problem will be a serious one.
The above problem (2) is caused by reducing the scanning lines from 1125 to 525, the above problem (3) is caused by reducing the scanning lines from 1125 to about 390, and the above problem (4) is caused by inserting periods having no picture in the upper and lower ends of the current display so as to display the whole of a picture of an aspect ratio of 16:9.
Although use of a down converter enables the current receiver to see a picture of the Hi-Vision system, the technique is not always sufficient.
As described above, when television receivers of the EDTV system and of the Hi-Vision system are adopted in the future, there is a possibility that there exist television picture display units of various modes and various kinds, in which, for example, the aspect ratio is a wide one of 16:9 and a current standard one of 4:3, the number of scanning lines is 1125 and 525, the scanning speed is a standard one and a double one, and so on.
Accordingly, it will become necessary to perform signal processing in accordance with the mode of the display picture plane of an individual one of such various kinds of television receivers. Further, the same applies to a television signal recording/reproducing apparatus, such as a VTR (Video Tape Recorder) and so on.